Units：练习题

Which of the following is the standard SI unit for gravitational field strength, g?

What is 0.000000025 meters expressed in nanometers?

A device measures the half-life of a radioactive substance to be \(72\) hours. If this time were expressed in seconds and placed in standard form, what would the power of ten be?

The unit for distance travelled is the metre (m). What is the corresponding derived unit for acceleration?

Voltage (potential difference) is defined as the energy transferred per unit charge. Given that the unit for energy is the Joule (J) and the unit for charge is the Coulomb (C), which derived unit is equivalent to the Volt (V)?

Show that the unit for acceleration (\(\text{m/s}^2\)) can be derived from the units of force (\(\text{N}\)) and mass (\(\text{kg}\)), given that \(1 \text{ N} = 1 \text{ kg m/s}^2\).

Explain why the derived unit for momentum, kilogram metre/second (\(\text{kg m/s}\)), is fundamentally equivalent to the unit Newton second (\(\text{N s}\)), based on the definitions of Force and Newton's second law.

A high-speed train travels a total distance of \(180\text{ km}\) in \(45\text{ minutes}\).

a) Calculate the average speed of the train in kilometres per hour (\(\text{km/h}\)).

b) Express the average speed calculated in part (a) in the standard SI unit of metres per second (\(\text{m/s}\)).